Self-positioning combination work holder and dressing ring for flat lapping machines



SQL

, INVENTOR.

l.. DAY

Filed Aug. le, 1965 SELF-POSITIONING COMBINATION WORK HOLDER AND DRESSING RING FOR FLAT LAPPINGWIAGHINES April 16, 1968 Us 4774,@ Mfr.

United States Patent O 3,377,750 SELF-POSITIONING COMBINATION WORK HOLDER AND DRESSING RING FOR FLAT LAPPING MACHINES Lawrence Day, Chicago, Ill., assignor to Spitfire Tool & Machine Co., Inc., Chicago, Ill., a corporation of Illinois Filed Ang. 16, 1965, Ser. No. 479,716 2 Claims. (Cl. 51-131) ABSTRACT OF THE DISCLOSURE A lapping -machine having a rotatable lap plate and a ypressure plate movable vertically with respect to the lap plate through a dressing ring and into a work loader, the dressing ring being connected to and movable with the pressure plate into and out of superimposed relation with respect to the work loader by 4a lost motion connection between the pressure plate and the dressing ring so that there results a free limited vertical movement between such parts and independent rotational movement of the dressing ring and the work loader when the latter two parts are in superimposed relation with respect to each other.

Summ'ary of the invention The fiat lapping machines now generally in commercial use employ a rotatable lap plate on which are supported one or more dressing rings. In addition to dressing the lap plate these dressing rings are employed for retaining work, within their confines, to be lapped by the lap plate and are generally rotated about a fixed axis by the rotation of the lap plate.

Within the dressing ring and upon the work being lapped, is arranged a pressure plate. This pressure plate is moved from and into position within the ring and upon the work by hydraulic lifting means in a manner such as is disclosed in Patent No. 3,032,937, dated May 8, 1962.

The operator utilizes a loading ring which is of the same size and shape as the dressing ring. The loading ring is placed upon a shelf of the machine at which time the work is confined therein. After being loaded, the operator slides the loading ring with the work confined therein from the shelf onto the lap plate. After attempting to accurately align the loading ring beneath the elevated dressing ring and pressure plate, he then removes the loading ring leaving the work remaining on the lap. After this has been done he then lowers the pressure plate which in turn lowers the dressing ring. When the dressing ring is in lowered position, it will encircle the work upon the lap if the work has been lproperly aligned with the dressing ring. The lap plate is then rotated to effect lapping of the work.

If the work is not in alignment with the dressing ring there is a possibility that as such ring is lowered to conline the work, the dressing ring will strike the work and damage the same. This is particularly true with respect to delicate work such as thin silicon wafers or the like.

It is therefore a principal object of my invention to provide a self-positioning work holder and dressing ring, comprising superimposed sections which cooperate with each other in such a manner that such sections will automatically align themselves to avoid damaging the work confined therein.

Other objects will appear hereinafter.

The invention consists in the novel combination and arrangement of parts to be hereinafter described and claimed.

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The invention will be best understood by reference to the accompanying drawings showing the preferred form of construction, and in which:

FIG. 1 is a perspective view of a lapping machine showing my invention associated therewith;

FIG. 2 is a fragmentary sectional detail View of a lapping plate showing my improved ring associated therewith; and

FIG. 3 is a sectional detail view of the ring embodying my invention showing the parts thereof in exploded position.

The self-positioning combination work holder and dressing ring embodying my invention is especially designed for use in a lapping machine of the type shown in Patent No. 3,032,937, dated May 8, 1962. The lapping machine there disclosed includes a base 10, a supporting plate 11 which is adapted to slidably support a workloading shelf 12. The base 10 rotatably supports a lap 13.

Hydraulically movable a supporting posts 14 each include a laterally extending arm 15 supporting a pressure plate 16. The post 14, of which there may be several, when moved upwardly under hydraulic pressure will move therewith the pressure plate 16.

My improved self-positioning ring is indicated at 17. It comprises two superimposed sections 18 and 19. The top ring section 18 has inwardly extending lugs 20 which are adapted to be engaged by the pressure plate 16 whereby movement of the pressure plate will impart movement to the ring section 18 upon engagement of the pressure plate with the lugs 20.

The ring 18 in its bottom peripheral edge 21 has formed therein an inverted V-shaped groove Z2. The bottom ring 19 has formed on its top peripheral edge portion 23 a V-shaped rib 24 which is adapted to interit in the groove 22 when the ring section 18 is positioned on the ring section 19.

-In use the operator positions the ring section 18 in an upper position as shown in FIG. 1. He places the ring section 19 upon the shelf 1.2. The top surface of the shelf 12 is in the same plane as the top surface of the lap plate 13. While the ring section 19 is upon the shelf 1Q, the operator will arrange in the ring section 19 the work pieces to be lapped such, for example, the silicon wafers.

After he has arranged the work pieces in the section 19, he will slide the ring section with the work therein olf of the shelf onto the lap plate to the position shown in dotted lines 25. He will attempt to align the ring section 19 with the ring section 18 as accurately as is possible. He next lowers the ring section 18 upon the ring section 19 with the pressure plate 16 positioned within the ring section 19 upon the work contained therein. The lap plate is now rotated in the manner shown in Patent No. 3,032,937.

If, however, the operator should fail to accurately align the ring sections 18 and 19' upon4 lowering of the pressure plate and the section 18, the rib 24 will engage the groove 212 of the section 18 in such a manner as to shift the ring section 19 and the work contained therein into proper alignment with the section 18.

By this simple arrangement, the Work to be lapped is prevented from being struck or contacted in a manner such as would damage the work as would the case where the conventional dressing ring is used. By constructing a combination work holder and dressing ring in the manner I have described I am able to lap relatively delicate and thin work without subjecting the work to possible breakage by contact of the dressing ring therewith.

The foregoing construction is highly efficient in use and economical in manufacture.

While I have illustrated and described the preferred form of construction for carrying my invention into effect, this is capable of variation and modification without departing from the spirit of the invention. l, therefore, do not wish to be limited to the precise details of construction set forth, but desire to avail myself of such variations and modilications as come within the scope of the appended claims.

Having thus described rny invention, what I claim as new and desire to protect by Letters Patent is:

1. A lapping machine having a rotatable lap plate, a stationary loading area to one side of the lap plate, a hydraulically operated lift arm adjacent to the lap plate and loading area and a pressure plate carried by the lift arm, wherein the improvement comprises:

(a) a dressing ring carried by the pressure plate and movable therewith through a substantially vertical plane with respect to the lap plate,

(b) a work loader in the form of a ring and of a size to `be positioned on the work loading area and freely movable therefrom onto the lap plate beneath said dressing ring,

(c) said work loader and said dressing ring having equal inner diameters so that when said work loader is moved onto the lap plate and said dressing ring is moved vertically with the pressure plate by said lift arm into a superimposed position, said pressure plate will move freely therethrough,

(d) means for connecting said dressing ring to the pressure plate for :moving the dressing ring vertically with respect to said work loader and for permitting independent movement of the pressure plate by the lift arm vertically through the dressing ring and into said work loader and independent rotational movement of the dressing ring and the work loader about the pressure plate,

(e) and means provided vby said work loader and said dressing ring cooperating to align their inner diameters vertically when said work loader and said dressing ring are in a superimposed relation so that the pressure plate rnay be moved by the lift arm through said dressing ring and said Work loader.

2. A lapping machine as defined by claim 1 wherein said means provided by said work loader and said dressing ring cooperating to align their inner diameters, cornprising a substantially V-shaped groove formed in one confronting surface of said dressing ring, and a substantially V-shaped rib formed in the other confronting surface of said Work loader, with said rib and said groove adapted to interlit when said dressing ring is moved into superimposed position upon said Work loader by the pressure plate.

References Cited UNITED STATES PATENTS 2,688,215 9/1954 Roshong 51-129 3,032,937 5/1962 Day 51-129 3,233,370 9/1966 Best 51-131 3,254,641 6/1966 Blaine 12S-15 3,304,662 2/1967 Boettcher 51--131 HAROLD D. WHI'IEHEA'D, Primary Examiner. 

